SVGBasics

Line Markers with SVG

Line markers are simple shapes placed regularly along a
path. This can be useful for giving directional arrows or
marking distance at a set interval.

If markerUnits is not specified, it defaults to
"strokeWidth" This means that 1 in a marker is
equivalent to the strokeWidth of the graphic that the marker
is applied to.

An arrow marker can be handy if you're trying to work
with a fill rule the evenOdd rule is confusing.

You may think, like I did, that a marker would be a great
user interface element to tie some scripting behaviour to. In
my case I thought it would be a clever place to have a user
click in order to move a vertex. Unfortunately, the
specification explicitly states that "Event attributes
and event listeners attached to the contents of a
'marker' element are not processed; only the
rendering aspects of 'marker' elements are
processed." To me, this doesn't leave a whole lot of
good uses for markers outside the originally intended use as
a generic arrowhead. I'd recommend their use when making
a callout box but for anything interactive you're going
to need a different element.